class_docstr: Base class for explicit Runge-Kutta methods.
code: def _dense_output_impl(self):
      Q = self.K.T.dot(self.P)
      return RkDenseOutput(self.t_old, self.t, self.y_old, Q)
  
imports: import numpy
  from .base import OdeSolver, DenseOutput
  from .common import validate_max_step, validate_tol, select_initial_step, norm, warn_extraneous, validate_first_step
  from .None import dop853_coefficients
label_desc: Use image node_id 5 for calling the RungeKutta obj's underlying member method code with example usage: obj._dense_output_impl() and returns: RkDenseOutput